The Constitution we recognise today was written in Philadelphia in during the summer of 1787. It is our second consiitution, the first, the Articles of Confederation and Perpetual Union was an agreement between the 13 original states that established the United States of America.
The Articles of Confederation were seen as weak and its structure was seen as incapable of manging the affairs of the newly establish nation. The framers sought a much stronger national government with a chief executive (a persident), courts and a way to raise money to support the new national government.
On March 4th 1789 the Articles were replaced with the Constitution we know today as the supreme law of the United States of America. The first three articles of the constitution concern the construction of the national government. Article I describes the Congress - the legislative branch of government; Article II enumerates the powers and responsibilities of the president - the executive branch; and Article III establishes the judicial branch of our national government and our court system.
The framers created a national government whose powers were limited by a system of checks and balances, that is, one branch to legislate, a second branch to see that the laws were faithfully executed, and a judiciary to interpret and apply the law fairly and equally.
Madison, who is often cited as the author of the model that our federal gpovernment is based upon, understood that our republlic works best in times of peace, when there is debate, compromise, and deliberation in forming rules, regulations and policies. However, in times of crisis decision making by committees might not prove adequate. And, the framers invested awesome powers in the persident to be used when needed.
According to the constitution the president is commander in chief of the United States Armed Forces, and when called into federal service the president commands the state militias.
Although the power to declare war is one of the enumerated powers of the Congress, the legislative branch, presidents have and continue to exercise war powers without congressional consent. The president may make treaties with the advice and consent of the senate, however presidents continually enter into accords and other agreements which they deem politically but not legally binding and therefore do not require, nor is the consent of the senate sought.
The persident apppoints ambassadors, and judges to the Supreme Court with the advice and consent of the senate, but is also allowed to make 'recess appointments' to fill a host of other high ranking government positions when the congress is not in session. This power is increasingly used to make more controversial appointments.
Although there is no mention of presidential legislative power in the constitution, persidents have used executive orders to legislate in all areas of American life. And, it is feared that the constitution and/or the bill of rights could be curtailed by use of this unennumerated power.
The power of the executive branch of our government has grown in size and authority well beyond anything imagined by the framers. It can also be stated the the legislative branch of our government has grown weaker than anything imagined by the framers, and our system of checks and balances has been eroded not only by executive expansion, but also by and congressional retreat.
As Madison, the architect of our federal system of checks and balances, stated during the Virginia Ratification debates, "I believe there are more instances of abridgement of the freedom of the people by gradual and silent encroachments than by violent and sudden usurpations."